mcp-eth-server

MCP (Model Context Protocol) server for Ethereum built with Rust and rmcp SDK (Streamable-http).

Features

Tools

• get_balance – Query ETH/ERC20 token balances for any address
• get_token_price – Get on-chain token prices via Uniswap V3 QuoterV2 (using quoteExactInputSingle for accurate single-pool quotes, base USDC or ETH)
• swap_tokens – Simulate token swaps on Uniswap V3 (constructs real transactions and uses eth_call - no on-chain execution)

Architecture

• McpServer - Main server wrapper supporting multiple transports
• EthServer - Tool router implementation with #[tool_router] macro
• Built with official rmcp Rust SDK
• Type-safe parameter extraction with JSON Schema generation
• Supports stdio and HTTP transports
• Async/await with Tokio runtime
• Structured logging with tracing

Quick Start

Prerequisites

• Rust 1.90.0 or later
• Ethereum RPC endpoint (Infura, Alchemy, or local node)
• Private key for transaction simulation

Setup

# Set Rust version
rustup override set 1.90.0

# Copy example config
cp config.example.yaml config.yaml

# Edit config.yaml with your settings

Get Sepolia ETH from faucets:

• https://www.alchemy.com/faucets/ethereum-sepolia
• https://sepoliafaucet.com/
• https://www.infura.io/faucet/sepolia

Build and Run

# Build
cargo build

# Run with default config (config.yaml)
cargo run

# Run with specific config
cargo run config.testnet.yaml
cargo run /path/to/custom-config.yaml

# Run tests
cargo test

Usage with Cursor

Add to your Cursor configuration:

{
  "mcpServers": {
    "eth-mcp-server": {
      "url": "http://localhost:8080/mcp"
    }
  }
}

Usage with MCP Inspector

# Install MCP Inspector
npx @modelcontextprotocol/inspector

# Run server
cargo run

# Connect Inspector to Streamable HTTP transport

Tool Examples

Example 1: Get Balance

MCP Request:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "get_balance",
    "arguments": {
      "address": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
    }
  }
}

MCP Response:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "content": [
      {
        "type": "text",
        "text": "Balance: 1234.567890123456 ETH"
      }
    ]
  }
}

With Token Address (USDC):

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "get_balance",
    "arguments": {
      "address": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
      "token": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"
    }
  }
}

Example 2: Get Token Price

MCP Request:

{
  "jsonrpc": "2.0",
  "id": 3,
  "method": "tools/call",
  "params": {
    "name": "get_token_price",
    "arguments": {
      "token": "WETH",
      "base": "USD"
    }
  }
}

MCP Response:

{
  "jsonrpc": "2.0",
  "id": 3,
  "result": {
    "content": [
      {
        "type": "text",
        "text": "WETH Price: $2,450.00 USD\nSource: Uniswap V3 QuoterV2 (WETH/USDC pool)\nMethod: quoteExactInputSingle"
      }
    ]
  }
}

Example 3: Swap Tokens (Simulation)

MCP Request:

{
  "jsonrpc": "2.0",
  "id": 4,
  "method": "tools/call",
  "params": {
    "name": "swap_tokens",
    "arguments": {
      "from_token": "WETH",
      "to_token": "USDC",
      "amount_in": "1.0",
      "slippage_bps": 50
    }
  }
}

MCP Response:

{
  "jsonrpc": "2.0",
  "id": 4,
  "result": {
    "content": [
      {
        "type": "text",
        "text": "Swap Simulation (Uniswap V3)\n\nInput: 1.0 WETH\nExpected Output: 2,438.25 USDC\nMinimum Output: 2,426.05 USDC (0.5% slippage)\n\nFee Tier: 0.05% (500)\nPrice Impact: ~0.02%\n\nGas Estimate: 150,000 units\nEstimated Gas Cost: 0.0045 ETH (~$11.00)\n\n⚠️ SIMULATION ONLY - Transaction not executed\n✓ Token approval may be required"
      }
    ]
  }
}

Testing

... [View full README on GitHub](https://github.com/0xByteLeon/mcp-eth-server#readme)